Abstract: In order to reduce the power loss of a direct current arc furnace the furnace vessel is only partially cooled in the region situated above the melting zone. A first cooling device is provided on a top edge of the vessel. A second cooling device is provided at the height of a slag line. The region of a vessel wall situated therebetween and facing the interior of the vessel above the slag line consists essentially of refractory material.

Abstract: A cooled bottom electrode for a direct-current electric furnace includes one or more steel bars incorporated in a refractory hearth of the furnace and having at least its upper end in contact with the bath of molten metal within the furnace, at least a first upper liquid part and at least a second lower solid part being defined along the steel bar and being divided by a separation zone, the lower solid part being associated with cooling elements. The cooling elements are copper cooling means elements introduced in cooperation with the solid part of the steel bar and being inserted at least therewithin and extending at least partly within the bar and towards the inside of the furnace. The copper cooling elements cooperate with a cooling-water system positioned below the bar and in cooperation therewith.

Abstract: In a method for manufacturing a base anode (10) having a multiplicity of adjacently arranged metal elements (11) for a metallurgical vessel (1), the intermediate spaces (14) between the metal elements (11) are filled with refractory material (16), the refractory material (16) being compressed. To achieve a high degree of compression in a short period of time, the compression of the refractory material (16) takes place by means of vibration.

Abstract: Two upper electrodes 16 and 17 are horizontally spaced apart from each other with a predetermined distance and vertically extend through a furnace roof 3 of a furnace shell 2. Upper conductors 20 and 21 are connected to the upper electrodes 16 and 17 and extend in a direction away from the upper electrodes 17 and 16, respectively. Two lower conductors 22 and 23 are connected to a lower electrode 1 and extend in directions along which the upper conductors 20 and 21, respectively. Power source circuits 24 and 25 are arranged between extension ends of the upper and lower conductors 20 and 22 and 21 and 23, respectively. Arcs 12a and 12b generated between the upper electrodes 16 and 17 and the lower electrode 1 are directed to a center of the furnace shell 2.

Abstract: A direct current electric furnace for melting ferrous raw material, such a scrap iron, comprising a vessel (1) closed by a detachable cover (13), at least one consumable electrode (5) which passes through at least one opening (16) in the cover (13), at least one stationary electrode (5) positioned in the bottom (2) of the vessel (1), and comprising at least one source of direct current, the vessel being defined by a bottom (2) in the shape of a basin (21) and by a lateral wall (12). The height (H1) and the cross-section (S1) of the basin (21) are determined by the conditions of use, such that the basin (1) (21) can contain a prescribed quantity of molten metal, the height (H2) of the lateral wall (12) of the vessel (1) being such that the vessel (1) can accommodate a sufficient charge of scrap iron (7) to produce, in a single melting operation, the prescribed quantity of a molten metal.

Abstract: A metallurgical container of the type having a vessel having a bottom wall and an inner refractory lining includes a hearth bottom electrode extending through the bottom wall and the lining and including, in a superposed condition, a bar and a connector. The bar is flush with the surface of the refractory lining. The connector is fastened to a lower surface of the bar, is internally cooled, has a diameter smaller than the diameter of the bar, and is attached to the bar at its upper front face at a level within the thickness of the refractory lining. A ring is interlocked to the vessel wall, surrounds the connector, and has an upper face located below the bar so as to be capable of carrying the bar. In order to prevent liquid materials from penetrating by infiltration between the bar and the ring, the bar is prolonged or elongated toward the bottom wall by a skirt which surround the connector laterally. The invention is particularly applicable to direct current operated steel plant arc furnaces.

Abstract: A method for carrying out post combustion in an electric arc furnace comprising forming a preferential gas stream within the electric arc furnace, concentrating carbon monoxide within the gas stream, and providing post combustion oxygen into the gas stream where the carbon monoxide is concentrated.

Abstract: A high-bandwidth continuous-flow arc furnace for stream welding applications includes a metal mass contained in a crucible having an orifice. A power source charges an electrode for generating an arc between the electrode and the mass. The arc heats the metal mass to a molten state. A pressurized gas source propels the molten metal mass through the crucible orifice in a continuous stream. As the metal is ejected, a metal feeder replenishes the molten metal bath. A control system regulates the electrode current, shielding gas pressure, and metal source to provide a continuous flow of molten metal at the crucible orifice. Independent control over the electrode current and shield gas pressure decouples the metal flow temperature and the molten metal flow rate, improving control over resultant weld characteristics.

Abstract: The method relates to the operation of a D.C. electric-arc furnace provided with at least one bottom electrode including an elongated metal current-supply body passing through the hearth of the furnace and surrounded by a casing made of dense refractory substance, comprising at least one shell ring whose upper end comes into contact with the molten metal in the furnace. During restarting of the furnace after shut-downs, a free expendable annular part made of refractory material, of flattened general shape, is placed on the upper end of the shell ring, which part extends it upwards and is intended to come into contact with the molten metal instead of said shell ring. The method applies in particular to D.C. electric-arc furnaces for the manufacture of steel, and is intended to reduce wear on the refractory parts surrounding the bottom electrode.

Abstract: A DC arc furnace according to the invention has a bottom electrode, which comprises a plurality of contact pins each having an end to be brought into contact with an object and to supply arc-forming current thereto, a current base electrically connected to the other end of each of the contact pins for distributing current from a power supply to the contact pins, and a cooling device for cooling the current base with the use of cooling water.

Abstract: Electric arc furnace with alternative sources of energy, which functions with direct current or alternating current and comprises at least one lance (12) to inject pure or combined oxygen above the bath (16) and a plurality of tuyeres (13) positioned in the hearth of the furnace (10) to inject oxygen below the bath, the tuyeres (13) being cooled by a peripheral movement of a cooling mixture consisting of at least one gas having a high cooling power (methane, butane, inert gases, etc.) and of at least one diluting gas (nitrogen, carbon dioxide), pipes (15) being included to introduce additives and powdered coal, post-combustion burners (28) possibly being comprised, the tuyeres (13) including an oxygen delivery pipe (18) having a diameter greater than 8 mm., the oxygen pressure being capable of being modulated according to the working steps, there being a constant minimum pressure of delivery.

Abstract: According to the present invention, there is provided a direct current electric furnace for melting metal capable of melting scraps rapidly and also capable of diminishing cold and hot spots formed on the furnace wall, wherein the direct current electric furnace is provided with a single top electrode, a plurality of furnace bottom electrodes, or a plurality of electrode units obtained by dividing a multitude of furnace bottom electrodes of a small diameter into plural units, and electric current controlling thyristor circuits for controlling each individually electric currents flowing through the plural furnace bottom electrodes or electrode units. The electric current controlling thyristor circuits may be substituted by thyristor circuits for controlling electric currents for each of plural groups obtained by dividing the above plural furnace bottom electrodes or the above many furnace bottom electrodes or the above plural electrode units into the plural groups.

Abstract: A bottom electrode (1) for d.c. arc furnaces with metal rods (3) arranged on the base plate (2) of the bottom electrode and with conductive and nonconductive layers formed of high temperature-resistant refractory material introduced between them. An upper layer formed of conductive bricks (8), a middle layer formed of conductive, monolithic lining material (9), and a lower layer formed of a nonconductive insulating mass (10) are introduced via the circumference of the base plate (2). In the area of the bricks (8), the metal rods (3) are additionally embedded in a nonconductive mass (11). To introduce inert gases to purge the melt through the bottom electrode (1), the metal rods (3) are provided with a cored hole and, in the upper part, with a number of radial holes in order for the purging gases to be able to be discharged in the area of the bricks (8), or blind holes (13), which are connected to a second purging gas line (13a), are introduced into the lower part of the lined bottom electrode (1).

Abstract: A direct current arc furnace is described with a cathodic electrode held in the center of the melting vessel and an anodic bottom electrode arrangement in the vicinity of an electrically conductive lower vessel from the vessel wall to the melt. The current supply and removal takes place on one side via leads to a rectifier power supply set up in spaced manner alongside the furnace. The lower vessel is connected in several quadrants with leads and in the vicinity of each quadrant a connecting plate is provided on the furnace wall. Close below the arc the power supplies are led in a horizontal plane to the furnace wall. The current intensity for the quadrants of the lower vessel adjacent to the rectifier power supplies is lower than that of the power supplies to the remaining quadrants. The spacings of the connecting plates for the quadrant areas can be unequal.

Abstract: For the purposes of better cooling and improving the starting conditions of a direct current arc furnace, there is provided a hearth electrode which comprises at least one metal bar passing through the hearth wall and which is cooled by at least one cooling duct which extends along the metal bar to the inner end thereof and opens into the interior of the furnace.

Abstract: An anode for a direct current arc furnace is proposed, in which at least part of the area of the furnace receiving the melt is provided on the inside with an electrically conductive refractory lining, which is electrically connected to the conductor located on the outside and in which a cathode is positioned vertically above the melt. The electrically conductive lining (3, 4; 9) and/or the conductor (1, 8) have varying values with respect to their electrical characteristics in the circumferential direction relative to the vertical axis of the cathode (2; 11), so that there is a planned, asymmetrical current distribution on the furnace bottom.

Abstract: Molten metal in an electric arc furnace is stirred by introducing a gas into the melt through tuyeres mounted in the hearth. Each tuyere has an inlet portion having a passage of relatively large diameter and an outlet portion having a passage of relatively small diameter. The tuyere is mounted in the bottom of the electric arc furnace with the inlet portion extending through the furnace shell and part of the refractory brickwork. With this design of tuyere gas at conveniently available pressure (16 bar A) can be fed to the tuyere and leaves the outlet portion at least at sonic velocity thus forming a relatively stable jet which inhibits molten metal entering the tuyere. The outlet portion may have a first portion with a slightly larger internal diameter than a second portion downstream of the first portion. When the second portion is fully eroded the flow of gas increases and triggers an alarm.

Abstract: An anode of a direct-current arc furnace is provided in the region of the bottom of the vessel, characterized in that a metallic, broom-like element, having bristles directed towards the interior of the vessel, is positioned in a region of the furnace vessel which is free of refractory material and subsequently, at least in the region of the broom-like element, refractory gunite is applied thereto and a metallic composition is admixed during the guniting, and as the thickness of the applied gunite increases, the ratio of the metallic composition to the refractory composition is reduced, gunite only being sprayed exclusively in the region of the inner edge of the ladle.

Abstract: A graphite block for an induction furnace in the form of a right prism formed from a plurality of plates associated along adjacent end faces parallel to the axis of the prism. Each plate includes a longitudinal recess opening into its top face adjacent a first end and a longitudinal recess opening into its bottom face adjacent an opposite end. Each end face is provided with a flexible graphite joint. The association of plates results from a partial interfitting of a top face longitudinal recess of one plate with a bottom face longitudinal recess of a second plate, the recesses being adapted to leave a void of polygonal section between the plates. This void is occupied by a graphite key of similar section divided over its length into two parts meeting along an oblique surface.

Abstract: A direct current arc furnace, includes a graphite cathode; and a container forming a hearth with a hearth base surface and having a container bottom acting as anode. The container bottom includes a supporting copper-plated sheet steel base consisting of a steel sheet and a copper plating plated on the steel sheet; electrical connection means extending through the steel sheet to contact the copper plating to supply an anode current to the copper plating; and a refractory brick lining having a graphite content above the copper-plated sheet steel base with the copper-plated layer adjacent the brick lining. In a preferred embodiment the graphite content in the brick lining decreases from the vicinity of the copper-plated sheet steel base to the vicinity of the hearth base surface.

Abstract: A wall electrode includes a metal bar adapted to extend through the wall of the furnace, a water-cooled sleeve composed of a material which is a good conductor of heat and electricity, an end member composed of a material which is a good conductor of heat and electricity, and an annular member such as a ring composed of a metal which is heavy and has a low melting point surrounding the bar so that the heavy metal in the liquid state spreads in the space between the bar and the sleeve when the annular member is made to melt during use of the electrode.

Abstract: In a segmented water-cooled induction melting crucible mainly used for melting special metals such as reactive metals or alloys, two adjacent segments are coupled as a segment having two legs, one leg having an inlet water passage and the other leg having an outlet water passage, so that these water passages form a one-way water flow path when they are connected. When the two legs are connected at their top portion to form a shorted portion, the lower end of the legs are insulated from each other and from a base forming a bottom of the crucible. Alternatively the two legs can be entirely separated by elongating the slit and the water passage formed in each leg can be connected throgh an insulative, connecting member.

Abstract: In direct-current arc furnace the arc is deflected in a direction away from the current supply means (19) through the action of the high-current lines (18) extending under the furnace vessel. This leads to the thermal overloading of a part of the furnace vessel walls. If the high-current lines (18a) are for the major part laid in a plane above the furnace bottom, on or below the furnace platform (20), and are taken downwards to the connection fittings (10) on the furnace bottom only on the side of the furnace vessel (1) opposite the current supply means, the arc will again burn symmetrically.

Abstract: A refractory is laid on a base plate provided with a connector for the connection of a power source apparatus. Many electrode pins are inserted through the refractory and fixed in the base plate at their lower ends. The base plate is made of a steel upper plate member and a copper lower plate member overlapped one on the other and the lower end portions of the many electrode pins are electrically connected to the lower plate member through the upper plate member. When a DC electric arc furnace is operated, the electric current supplied to the connector reaches all the electrode pins mainly through the lower plate member in the base plate and flows from there homogeneously through the pins into the molten metal pool in the furnace.

Abstract: The present invention has been devised to obtain a metallurgical effect by introducing refining gas into a molten metal in a metallurgical vessel and stirring the molten metal sufficiently by convection, and to improve durability of one nozzle or a few nozzles for introducing the refining gas. At a predetermined position of a furnace bottom onto which a ramming mass is provided, a few cylindrical refractory sleeves are disposed close to the upper face of the furnace bottom from the lower portion thereof. In each cylindrical refractory sleeve a gas introducing nozzle, which introduces the refining gas, is disposed in such a manner that it can be drawn out downwardly for replacement.

Abstract: A direct-current electric arc furnace has an at least one electric arc electrode switched as a cathode and a bottom electrode switched as an anode. The bottom electrode includes an electrically conductive bottom plate, a first ramming mass consisting of electrically non-conducting refractory material centrally located atop the electrically conductive bottom plate, and a second ramming mass consisting of electrically non-conducting refractory material, the second ramming mass being located atop and about a periphery of the electrically conductive bottom plate.A plurality of concentrically arranged electrode segments are positioned between the first and second ramming masses, each of the plurality of electrode segments including an electrically non-conducting ramming mass configured to support a plurality of vertically arranged and electrically conducting segment conductors.

Abstract: A direct current arc furnace has a furnace vessel which is surrounded by a metal shell having at least one electrode connected as a cathode, and at least one bottom contact. The bottom of the furnace consists of a lining layer which possesses electrically conducting bricks or the like, which lining layer lies on a contact plate covering most of the bottom. The contact plate forms the bottom contact connected as the anode and lies on a bottom plate. The bottom plate is equipped with a plurality of connection fittings which pass through openings in the bottom plate and are connected via electric wires to a current supplying device provided next to the furnace. For the internal deflection of the arc, at least one section of the lining layer is composed of a material which possesses a lower electrical conductivity than the lining layer in another section which is circumferentially spaced from the one section so as to form circumferentially spaced zones of varying conductivity.

Abstract: The invention is directed to improved centrifugal rotary electric furnaces which are used for the heating and or fusion of minerals, such as quartz, and other materials having a high melting point. The furnace includes a generally cylindrical furnace shell and a decreasing diameter stepped end member attached to each end of the shell which is intended to more closely conform the end of the furnace to the shape of fused ingot or melted charge formed inside the furnace, while still providing a sufficient depth of unmelted charge between the fused or melted material and the end member to insulate the end member from excessive heat and the warpage and other damage caused thereby.

Abstract: A metallurgical vessel (10) includes at least one metallic electrode (20) fastened thereto having a chamber within the vessel (10) for holding a melt (19) and having a bottom surface, a shell (14) abutting the bottom surface, and a flanged tube (31) arranged on the shell (14) with the flanged tube (31) having a flanged surface (32). The electrode (20) is disposed coaxially with respect to the flanged tube (31) and is formed by first and second bars (21, 22) connectable to one another. The first bar (21) has the top face positioned proximate to the bottom surface of the chamber and penetrates the vessel (10) for contact with the melt. The second bar (22) is positioned against the bottom face of the first bar (21) and extends out from the vessel (10), the first bar having a should region (23) positioned annularly thereabout adapted to contact and lean against the flanged surface (32) of the flanged tube (31).

Abstract: A furnace lining is formed by a plurality of lining bricks. The bricks have surfaces defining an internal surface of the lining that is to face the interior of the furnace and to receive therefrom radiant heat. At least one depression is formed in the lining and opens onto the surface through an opening. The depression has internal wall surfaces that are geometrically configured to cause radiant heat from the furnace interior that impinges on a first internal wall surface to be reflected thereby and to impinge therefrom onto a second internal wall surface. Thus, the heat will be absorbed by the bricks of the lining, and such heat will be emitted thereby from the inner surface thereof.

Abstract: A method and apparatus for feeding iron-bearing particles into a metallurgical furnace such as an electric arc furnace, comprising a vessel for containing a bath of molten iron, having a wall extending above the bath of molten iron, a preferably screw type feeder mounted on the exterior of the vessel, a feeding port in the vessel wall shaped to permit passage of the feeder into the interior of the bath of vessel and located at such a height from the molten iron so that no molten materials will spill out from the furnace through the port during the normal operation and maneuvering of the furnace; and actuating means for extending the screw type feeder from a retracted position out of the vessel to an extended position into the vessel.

Abstract: A lining for a direct-current electric-arc furnace, in which at least part of that regions of said furnace which receives the melt is provided on the inside with an electrically conductive, refractory brick lining and a ring-shaped current conductor, on its outside, constitutes the opposite pole to the upper electrode centrally extending into said surface. The entire bottom area is covered with a refractory, insulating brick lining and a brick lining of graphite bricks is applied onto that brick lining in the radially outer wall region of the furnace. Located adjacent thereto in radially inward manner is an annular zone, comprising an electrically conductive, refractory brick lining. The central bottom area above said insulating brick lining is consittuted by a monolithic ramming mass. Furthermore, the material of the wall of said furnace above said brick lining of graphite bricks largely corresponds to that of said insulating brick lining at the hearth bottom.

Abstract: The invention provides a direct current electric arc furnace which is composed of a feeding system of direct current to the furnace, a movable electrode at the roof of the furnace, and a bottom electrode attached to the bottom of the furnace at the position deviated from the center of the bottom of the furnace, the deviated distance from the center being determined by a magnetic field, generated by a current in the steel bath of the furnace, from under an arc generated by the movable electrode to the bottom electrode, which can cancel a second magnetic field generated by the current of the feeding system.

Abstract: A furnace bottom structure of a direct current electric furnace has at least one furnace bottom electrode and at least one gas injection tuyere provided in the furnace bottom refractory of the direct current electric furnace. Preferably, the furnace bottom electrodes and the gas injection tuyere are embedded in a substantially cylindrical refractory body with downwardly diverging tapered upper portion. The refractory body, the furnace bottom electrodes and the gas injection tuyere form an integral furnace bottom block which is detachably attached to the bottom of the electric furnace so as to close a bottom opening of the furnace.

Abstract: In a direct-current electric-arc furnace, the bottom contact, that is the hearth electrode, must be insulated from the metallic shell of the furnace vessel by insulating material. For this purpose, the bottom plate carrying the bottom contact essentially forms the bottom of the furnace vessel. This bottom contact, with an insulating material, or a material which is at least a poor electrical conductor, inbetween, rests on a part, projecting radially inward, of the metallic vessel shell.

Abstract: The metallurgical vessel, such as a direct-current arc furnace, comprises a metal housing (1) lined on its inside with refractory material (2), at least one electrode (3) passing through the bottom of the vessel and connected to a terminal of an electrical power supply, the electrode being fastened to the metal housing by a mechanical fastening arrangement and insulated electrically from the housing. A leaktight wall (20) surrounding the fastening zone of the electrode prevents a liquid flowing over the inner surface of the housing from coming into contact with the electrode fastening arrangement, and orifices (26) are provided for discharging the liquid collected out of the housing. The invention is particularly applicable to direct-current arc furnaces and prevents the molten lead originating from the scrap metal of the charge and infiltrating through the refractory from damaging the electrical insulation of the fastening of the electrode.

Abstract: The service life of a bottom electrode for a direct current arc furnace for producing steel is prolonged by using ZrB.sub.2 type sintered bodies for a contacting pins which constitutes a major part of the bottom electrode wherein the ZrB.sub.2 type sintered bodies have a corrosion-resistance to molten steel and slag. Further, the number of contacting pins to be used is reduced by forming each of the pins into a form of pillar with a through hole at the axis, or by assembling a plurality of longitudinally divided pin portions to form a contacting pin, whereby the diameter of the contacting pin can be made large. Then the space between contacting pins is made broad, and brick having good corrosion-resistance are filled in the space so that the service life of the bottom electrode is brought closer to that of the refractory lining of the direct current arc furnace.

Abstract: In a direct-current arc furnace having a bottom electrode (2), electromagnetically and/or chemically induced bath agitations are substantially eliminated by an electromagnet (9) arranged under the vessel bottom (7). In this way the stability of the bottom electrode (2) is considerably increased. The electromagnet (9) is preferably integrated into the electrical supply of the furnace and serves as a smoothing choke.

Abstract: The electric connection device comprises an electrode (5), a sleeve (19) mounted around a projecting end part (8) of the electrode (5), and an arrangement for cooling the sleeve (19) with a cooling fluid comprising at least one system (20, 20') of nozzles (21) spraying cooling fluid onto the outer surface of the sleeve (19).

Abstract: A cover for a vessel handling heated substances, such as a furnace, in which the cover comprises an outer segment defining an opening in which a removable inner cover segment (delta) is seated and wherein said inner cover segment comprises spaced apart walls defining an enclosed space that contains coolant spray means adapted for spraying coolant onto the wall that is closest to the interior of the vessel.

Abstract: A process for casting an ingot of pre-alloyed metal from a consumable electrode. It includes the steps of: providing a consumable electrode corresponding to the desired metallurgical composition of the to-be-cast ingot; providing a second electrode; striking an arc between the consumable electrode and the second electrode to melt the consumable electrode and thereby form a molten pool; maintaining the arc between the consumable electrode and the molten pool; rotating or oscillating the consumable electrode about its axis during melting; providing a controlled atmosphere for the melting of the consumable electrode; delivering molten metal into a fluid cooled mold; and withdrawing the ingot from the mold.

Abstract: An anode for a d.c. arc furnace is described. The furnace area receiving the melt (2) is provided on the inside with an electrically conductive, refractory lining (8,9,11). The latter is electrically connected to a conductor (12) located on the outside and which has a cylindrical construction and is placed around the electrically conductive lining. The conductor is advantageously fixed to the inside of the steel jacket (3) of the furnace.

Abstract: The excessive wear and formation of ring-like cavities in carbon crucibles used to contain iron-based compositions that are heated in a plasma furnace to a temperature of from about 2000.degree. C. to aboout 2700.degree. C. are reduced or eliminated by adding carbon particles to the crucible in amounts of at least about 6 weight percent of the melt, and preferably in amounts exceeding the solubility of carbon in the heated melt.

Abstract: A wall electrode for a D.C. powered electric arc furnace for the processing of metals in a liquid state, especially steel. The electrode is constituted mainly (a) by a metallic bar (4) one of whose ends comes into contact with the metallic bath (6), while a portion (7) of its other end extends to the exterior of the furnace; (b) by a sleeve (8) of thermally and electrically conductive material, energy-cooled by a flow of cooling fluid, surrounding the portion (7) of the other end of the bar at a distance therefrom; (c) by a nipple (9) of good electrically conductive material extending the aforementioned portion (7) of the other end of the bar; and (d) by a connection of the nipple and the sleeve to the same bar of an electrical supply.

Abstract: Apparatus for the thermal treatment of a metallic melt includes a metallurgical vessel (10) for receiving the melt; a D.C. arc heating device for heating the melt includes at least one electrode (20) positioned above the melt and at least one counterelectrode (22) in contact with the melt; a first element located on the outer jacket of the metallurgical vessel for transferring electrical energy to the counterelectrode; a second element (40) for transferring electrical energy to the first transfer element (30); and a compensation or equalizing element (45, 44) operatively connected to the second transfer element for mechanically positioning the contact plane of the second transfer element in electrical energy conducting relation with the contact plane of the first transfer element.

Abstract: An upper electrode is mounted in the upper portion of a furnace and a bottom electrode is mounted in a bottom of the furnace. An electric arc is generated by introducing electric current to the upper and bottom electrodes and the raw materials charged in the furnace is melted. In the process of melting the materials, a mist of cooling water is sprayed by spray nozzles directly against the lower portion of the bottom electrode extruding downwards and the bottom electrode is cooled by the mist.

Abstract: The bottom of a solid metal charge melts to fill a form below the charge. During melting, usually, the metal that enters the form remains continuous with an unused solid part of the charge. After cooling, the formed metal is removed together with the unused part of the charge--and usually with the form too. They are separated later or in a different operation, and another charge is positioned immediately for melting into another form, so the useful duty cycle is very high. A preferred form of the invention uses an upper melting chamber and a lower forming chamber, separated by a horizontal wall but communicating by an aperture through the wall. The charge and form are placed against the wall from below to block the aperture. The charge preferably extends up through the aperture into or toward the melting chamber, where an arc electrode or other heater melts the top of the charge, particularly near its center.

Abstract: A refractory heat-insulating graphite sheet material characterized in that the material comprises a graphite sheet.

Abstract: An improved electric arc furnace provides increased capacity and reduced operating costs. The furnace has an ob-round shape which locates sidewalls further from the source of heat. The improved furnace can accept a larger scrap charge and provides a larger surface area for slag reactions to take place. All of these advantages are obtained without the need for building new foundations or ancillary equipment.

Abstract: An electric arc furnace includes a crucible having a metal shell for recovering precious metals from spent material. The shell includes a metal tap hole and a slag door positioned above and opposite the metal tap hole. A removable swinging roof is provided above the crucible together with a plurality of electrodes for heating the spent material. Also, a cooling band circumscribes the crucible for cooling the metal shell. Conveyors are provided for distributing the spent material at a plurality of points located between the electrodes and the wall of the crucible. The crucible is tilted to allow the removal of the slag and metal.